Isengrim Took III was the eldest of the twelve children of Gerontius, the Old Took, and became Thain in S.R. 1320 at the age of eighty-eight when the Old Took died at the end of his seventy-two year reign at the age of 130.

Isengrim became the 27th Thain of The Shire - 15th in the Took line - but due to his old age at the time of becoming Thain, he only stayed in office for ten years, dying at the age of ninety-eight. He left no heir, and as far as we know he never married, so the Thainship passed to his younger brother, Isumbras.

Etymology

"Isengrim" is of Anglo-Saxon origin and comes from isen meaning "iron" and grim meaning "fierce".

It is likely Isengrim is named after an earlier , but it is notable that "Isengrim" is the name of a wolf who appears in many medieval epics, including the story of Reynard the Fox which originated in French folklore.